My truck has 210k miles on it but I have towed at the max both my truck and trailer at 13k pounds. I'd say you are probably going to be pushing it if the trailer alone is 13k #'s. If it was me, I would be looking for a diesel. Even pulling my 7x16 enclosed, my truck pulls it very nicely but I would still rather have a diesel. If I were pulling that much weight on a regular basis I wouldn't be happy with it. Just my .02 though.

As far as costs and such, the mileage sucks on them also. I average on the highway doing 65-70 with no load right around 13. With my trailer I get about 8-9mpg.

If its a legit 12000 trail. You need a bigger tk we tow our 10500 skid with a 3500 dually with a 6.0 and its a dog. Try that with a few other 6.0s we got and same thing...better get out a push at times
Oil changes. 6qts and a filter,,,price is all in what oil u get
I would look into something else. Just my .02Posted via Mobile Device

sounds like you guys need diesel trucks lol....I tow a skid steer a few times a week, a mini x a few times per week, my buddy's 7x14' 14k dump trailer loaded about 1ft-2ft over the sides with oak, and my 96 f350 diesel does it pretty well stock. so at time's i'm towing closer to 15,000lbs fuel economy is garbage but i really don't care about that, its factored into my jobs. but i would go turbo diesel. You need the torque!!!!